Basement of the Brothers Strong
From Homestar Runner Wiki
The basement of the Brothers Strong is where Strong Bad, Strong Mad, and The Cheat hang out, watch telebision, and play the Trogdor game. Many things happen down here, including (but not limited to) The Cheat lying in a crisper drawer. Strong Bad sleeps on the couch, as shown in the emails "cheatday", "other days", "morning routine", "underlings" and in the short "The Li'l Brudder Show". It was revealed in couch patch, that Coach Z threw up into the patch-covered rip in the couch after eating some of Strong Bad's gumbo. There must be two ways into the basement, as characters have been seen entering from both sides of the room. The basement has a drop ceiling and fluorescent lighting (as shown in couch patch and Strong Mad's Character Video).
According to the Easter egg in Nighttime Driving Type Game, Strong Bad's room is in the basement of the house. This is confirmed in nightlife, when Strong Sad enters Strong Bad's bedroom from the main room. However, it is contradicted by Strong Bad's Cool Game For Attractive People, which puts it on the first floor.
Part of The Brothers Chaps' office, shown in Making of Email 100, has the walls painted with the same design as Strong Bad's basement. The stripe on the wall is almost identical to the stripe in the downstairs residence on the 1980s sitcom Too Close For Comfort.